SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84dcee02a63e0bef76597ccae1ac88f8c76426267e7fbf6306751059bf8ae5d1' 
  AND token = 'MkpgH9cvdxDFH4XAujkDt2M4DFWn9ZDy4dT0ChhSY0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}